A lighting device of the kind set forth is known from U.S. Pat. No. 6,270,236. That document discloses a lighting device including a transparent carrier panel provided with transparent electrically conductive structures (e.g. an ITO layer) on one of the panel surfaces. On the carrier panel an LED—with terminals on both sides of a light emitting side—is mounted in such a way that the terminals are in contact with the conductive structures via a conductive adhesive (e.g. a soldering bump.) In particular, the conductive structure may have an additional electrically conductive contact pad in the form of a metal coating in the area of contact with the terminals of the LED. The advantage of this approach is disclosed to be an increase in contact stability.
However, experience shows that the increased stability provided by the metal contact pads in the direct vicinity of the LED terminals is limited. Due to the low conductivity of the ITO layer (R□˜15 Ohm) the lighting device is prone to failure. Especially under high current testing and over lifetime, the device fails as the electrical contact of the LED with the contact pad/ITO layer is lost due to very local heat dissipation.